Constructivism is a learning theory where students actively construct their own understanding and knowledge through experiences and reflecting on those experiences, such as completing projects and experiments using real-world problems. Key aspects include students learning in social contexts with more knowledgeable others, developing understanding within their zone of proximal development, and gaining legitimate peripheral participation through cognitive apprenticeships and situated learning. Teachers can support constructivism by integrating different projects for students to work on using their experiences and instruction to solve real-world problems.